Automatic tappet



March 31, 1953 H. H. ENGEMANN 2,633,112

AUTOMATIC TAPPET Filed June 22, 1950 2 SHEETS- SHEET l March 31, 1953 H-H. ENGEMANN AUTOMATIC TAPPET 2 SHEETSSHEET 2 Filed June 22, 1950 1 2172271 Eerie/ 1H Eye/WW2 Patented Mar. 31, 1953 UNITED si" 'i'S PATENTOFFICE assig'nor to Thompson Products, Inc., Cleveland, Ohio, atcorporation'of Ohio Application June '22, 1950, Serial No. 169,543

.1 Claim.

This invention relates to clearance regulators or lash adjusters havingconstant clearance controls which will absorb irregularities to preventover-control by the regulators or adjusters.

I Specifically, this invention deals with valve linkages havingautomatic clearance regulators wherein a load transmittingbi-symmetrical deflectable member is included in the linkage to maintaina constant clearance. I

Automatic clearance regulators or lash adjus'ters inherently take uplooseness or play by maintaining a' load on extensible parts under allconditions of operation, so that any irregularities in the operatingmechanism will cause the regulator or adjuster to function therebyproducing an undesired tightness in the linkage and frequentlypreventing'full seating of the linkage operated parts such as valves orthe like. In other words, the clearance regulator cannot distinguishlooseness or play due to cam irregularities from looseness or play dueto thermal expansion.

The present invention now provides a safety device which preserves apredetermined or constant clearance in a linkage including a clear-.ance regulator, thereby insuring proper operation of parts such asvalves actuated by the linkage. This safety device includes a'fiatspring washer transmitting spring load between its .outer and innerperipheries for preventing looseness in the linkage but capable of beingdeflected under increased loads to transfer such loads as" a solidunyielding member. The spring washer is iii-symmetrical (i. e. can beused in reversed positions with the same results),, is easily assembled,and is inexpensive.

It is, then, an object of this invention to (provide a safety device ina linkage including an automatic clearance regulator for creating apredetermined or constant operating clearance in the linkage withoutpermitting looseness or play to develop in the linkage.

Another object of the invention is to provide a 01169131608bi-symmetrical safety device requiring no manual adjustment formaintaining a predetermined or constant valve operating :clearance in avalve linkage .having an (automatic clearance regulator.

A further object of the invention is to permit the use of an automaticvalve :clea-rance -regulator a valve linkage actuated "by :a cam shaftdesigned to create specified valveoperating-olearance,

.=A further object of the invention is to provide iaaspacing devicewhich does not depend on speci- 2 tfied seating surfaces which inproduction might vary considerably.

Another object of the invention is to provide a bi-symmetrical constantclearance regulator coacting with inclined seating surfaces which onlycontrol the operating limits of the device.

Other and further objects of the invention will be apparent to thoseskilled in the art from; the following detailed description of theannexed sheets of drawings which, by way of preferred examples only,illustrate several embodiments of the invention.

As shown on the drawings:

Figure 1 is an elevational view, with parts in vertical cross section,of a valve linkage having a mechanical type of automatic valve clearanceregulator including the spacing device of this invention;

Figure 2 is an enlarged fragmentary cross-sectional view, with parts inelevation, showing the spacing device of this invention on a largerscale and in an unloaded condition;

Figure 3 is a view similar to Figure '2 but illustrating the spacingdevice in partially loaded condition;

Figure 4 is a view similar to Figure '2 but illustrating the spacingdevice in fully, deflected condition';

Figure 5 is an elevational View, with parts in vertical cross section,diagrammatically illustrating the spacing device of this invention in-.corporated ina'v'alve linkage outside of the automatic valve clearanceregulator but working in conjunction with the regulator.

Figure 6 is a typical load-deflection chart of the spacing devices ofthis invention.

As shown on the drawings:

In Figure 1,, the reference numeral I'll designates generally amechanical type of automatic valve tappet slidablymounted in an engineblock 13 andactuated by a cam shaft H. The tappet, in turn, .actuates apush rod [2 which transmits reciprocating .motion to an adjusting screw13 .in the end of a rocker arm M which opens a poppet valve l5 againstthe load of a valve spring 1.6..

The cam shaft H has the major portion of its circumference, designatedby the angle a, constituting a base circle having no valveyopeningeffect on the valve linkage. .Aoam lobe 1| la on the cam shaft isefiective to actuate the .linkage for "opening the valve and this lobehas an angular displacement :designated at b. .As :the base circleapproaches and leaves the :cam lobe l Ia, deflection take up andreleasing areas "known as opening and role-sing ramps, are protion 230of the nut.

The automatic tappet It] includes a stud or screw element 22 and a nutelement 23 in free threaded engagement on the screw, together with atorsion spring 24 having one end anchored in the screw and the other endanchored in the nut for urging the threaded together parts in anunscrewing direction to increase their effective length.

The screw 22 includes a cylindrical shank 22a,

an intermediate helically grooved head 22?), a

threaded portion 220 above the head, and a sec- .ond cylindrical shank22d above the threaded portion and projecting out of the upper end ofthe cup II.

The nut 23 includes a hollow internally threaded cylindrical portion 23awith a helically grooved :localized area 232), an outturned disk flange23c fitting freely in the cylindrical lip 2! of the cup, and a recessedcylindrical rim 23d projecting above the central portion of the flange230.

The lower end portion of the torsion spring as has several turns thereofseated in the grooves of the grooved head portion 22b of the screw andhas the lower end thereof anchored in a recess in the screw. The upperend portion of the torsion spring has several turns thereof seated inthe grooved portion 23b of the nut and has the upper end thereofanchored in a hole in the disk por- After the nut is threaded on thestud, the torsion spring will be wound up tending to rotatively drivethe stud to take up slack in the valve linkage.

The shank 22a of the screw slidably guides an inertia hammer sleeve 25with a helical cam .shaped recess 2 cm the bottom thereof and an.axially grooved recess 2% extending inwardly from the top thereof. Apin 26 on the shank 22a fitsin the recess a. The pin 26 is firmlyanchored in the shank 22a.

A second pin 21 projects into the slot 251) and ,through a helicalopening 28 in the shank 22a.

The upper end of the sleeve 25 is recessed at 250 to a depth beyond thelower end of the opening 28 and a coil spring 29 on the shank 22a hasone end thereof bottomed against the head 22?) and has the other endthereof projecting into ,the recess 25c and .bottomed on the pin 21.

The inertia hammer sleeve is effective for shortening the over alllength of the screw and nut assembly under the influence of inertiaforces produced by the acceleration and deceleration of the tappet H!such as occur during the normal cycle of operation of the valve linkage.In each fined to movement along an axial path by the pin 21 and axialslot-25b receiving this pin.

When the sleeve 25 is displaced upwardly, only axial movement will occuruntil the bottom of the slot contacts the pin 2'! thereby causing thepin to rise in its slot 23 and due to the helical conmovement will takeplace of the hammer sleeve 25. The rotative movement of sleeve 25 has noparticular function during this upward movement of sleeve 25, but theaxial component of the impact force of the sleeve is cushioned by thespring 29.

When the sleeve 25 shifts downward on the screw 22, it again follows asubstantially axial path throughout the major portion of its movementuntil the helical portion of the recess 25a strikes the pin 26 andexerts a rotating force on the screw in a direction tending to threadthe screw further into the nut. Further, this downward impact produces atorsional reaction force on the sleeve 25 itself, which tends toangularly twist the guide pin, and, since any angular movement of thisguide pin is confined by the slot 28 to movement along a helical path,the spring 29 will be compressed to also cushion the impact of thesleeve upon the pin 26.

It should therefore be understood that the torsion spring 21?. tends toelongate the valve linkage between the cam shaft II and the rocker armscrew l3, while the inertia sleeve 25 tends to shorten this linkage.

In accordance with this invention, the bottom face of the disk flange230 on the nut 23 is provided with an upwardly sloping face 39 and aflat lay-symmetrical spring washer 31 is positioned between this slopingface and the sloping shoulder 20 of the rib 19. This spring provides theconstant clearance feature of this invention.

A cap member 32 is seated on the shank end 22d of the screw and has arounded recess 32a receiving the lower end of the push rod 12.

In operation, the cam lobe Ila lifts the cup IT to first seat the washer3! on the shoulder 23 and to then raise the nut 23. The nut, in turn,lifts the screw 22 which, of course, raises the cap 32 to lift the pushrod and rocker arm screw IS. The rocker arm then opens the valve l5against the load of the spring l6. During that part of the opening andclosing stroke at which the tappet is subjected to deceleration, theinertia sleeve wvill rise toward the head 2212. But during the last partof the closing stroke when the tappet is subjected to acceleration, thisacceleration will cause the inertia sleeve to create an impact causingthe linkage to decrease in length between the cam and rocker arm screw.Then near the end of the valve closing cycle, as the load of the valvespring [6 is removed from the linkage, the torsion spring 24 will beeffective to elongate the linkage to reclaim any looseness. However, theelongation will continue as low spots on the base circle a 'of the camshaft ll ride over the bottom wall [8 of the cup or as irregularities inthis bottom wall create looseness or play. Then, when the cam lobe Ilaagain approaches the bottom wall l8 on the next valve opening cycle, thelinkage will be too long and the valve will start to open as theapproaching ramp 0 rides on the tappet wall and, in exaggeratedcondition, the valve may even be partially cracked or opened while thetappet is still riding on higher spots in the base circle of the camshaft.

This inadvertent opening of the valve or prevention of full valveseating is eliminated by the constant clearance regulator of thisinvention as illustrated in Figures 2 to 4.

In Figure 2, the spring washer 3| is in an unloaded condition and hasits outer periphery seated on the outer end of the sloping shoulder 20while its inner periphery is seated on the inner end of thesloping underface 3i of the disk tour of this slot, a rotative and vertically upwardu fiangefic while the slope angle of the shoulder and under face areillustrated as being the same, maintenance of such condition is notessential.

The slope of the shoulder 20 is designed as to give an operating gap Gbetween the cup I! and the nut 22.

In order to eliminate any looseness in the valve linkage, the torsionspring 24 of the clearance regulator is tensioned so that it will causerotation of the screw 22 in the nut 23 to increase the effective lengthof the linka e and partially deflect the spring washer 3 I to theposition shown in Figure 2, thereby decreasing the gap from G to G (Fig.3). This will place a small load in the linkage which, however, is notsufficient to influence the action of the valve spring l6 in holding thevalve in its fully closed or seate position.

When the cam lobe Ila actuates the tappet, the spring is completelydeflected to a full seating position on the shoulder 20, therebyreducing the gap to zero as indicated at G0 in Figure 4. In thisdeflected position, the spring 3| becomes a rigid member transmittingmotion without absorption between the cup I! and the nut 23.

As the cam lobe passes ofi of the bottom l8 of the cup [1, the spring 3|will reclaim the position shown in Figure 3 to provide the ga G in thelinkage. This gap will be sufficient to accommodate irregularities dueto run out conditions, low spots in the base circle, deflection of thecam shaft, and the like variations without permitting the clearanceregulator to elongate the linkage but at the same time preventinglooseness in the linkage.

In the modification shown in Figure 5, parts identical with partsdescribed in connection with Figure 1 have been marked with the samereference numerals. As shown in Figure 5, the flange 230 of tappet nut23 is seated directly on the thickened portion or rib I9 of the cup I!and the push rod I2 acts on the adjusting screw I 3 through the media ofa separate constant clearance regulator 40. This regulator 40 includes ahousing piece 4| with a rounded recess 4 la in the upper wall thereofreceiving the adjusting screw I3, a cylindrical recess 4Ib extendinginwardly from the bottom wall thereof receiving the upper end of thepush rod and a tapered or sloping bottom face 4lc converging toward therecess Mb.

The push rod has a collar l2a thereon with a sloping top face 12bparallel with the bottom face Ma 01 the housing. A flat spring washer 3|is disposed around the upper portion of the push rod and has its innerperiphery seated on the collar face l2b while its outer periphery isseated on the outer end of the tapered bottom face M0. The tapered facesprovide an operating clearance gap and the washer 3| will deflect in thesame manner as described above in connection with Figures 1 to 4 tomaintain an initial light load in the assembly for preventing loosenessand to provide a constant clearance in the linkage that will eliminateover-elongation of the clearance regulator Ill.

The chart of Figure 6 illustrates a typical load deflection curve forthe bi-symmetrical spacing device of this invention. As shown in Figure6, deflection of the spacing device in inches is plotted against load onthe spacing device in pounds. The curve as shows that at a 6 pound loadthe spacing device will deflect .004 inch, while, at 30 pounds load, thedeflection will be .012 inch. The spacing device will therefore have anoperating range of .008 inch between the initial deflection shown inFigure 3 of the drawings and the complete or valve opening deflectionshown in Figure 4 of the drawings. Of course, it should be understoodthat this chart is only an example of a typical installation and thatthe stiffness of the spring can be varied as desired to producedifferent load and deflection characteristics.

The safety device or constant clearance regulator of this invention isadapted for use in combination with any type of clearance regulator andthe illustrated mechanical torsion spring loaded and inertia hammeroperated tappet is only intended as an example of an operative device.The constant clearance regulator is also operative with hydraulictappets and push rods as Well as mechanical regulators of various typesnow known in the art.

It should therefore be understood that the invention provides a simple,inexpensive, bi-symmetrical constant clearance regulator for a linkageincluding an automatic lash adjuster or clearance adjusting device.

It will be understood that modifications and variations may be effectedwithout departing from the scope of the novel concepts of the presentinvention.

I claim as my invention:

A valve clearance regulator comprising a housing cup having an open endwith an adjacent internal sloping shoulder, said housing adapted toreceive actuating forces to be transmitted by the valve clearanceregulator, threaded together screw and nut elements in said cup, atorsion spring anchored on said elements tending to unscrew the sameinto an elongated condition, an inertia hammer on the screw parts actingto thread the elements together into a foreshortened position, said nuthaving a flange overlying said shoulder, and a bi-symmetrical springwasher disposed between said flange and said shoulder for transmittingload between the cup and nut and for deflecting to absorb some of theload without transmitting movement, whereby spurious forces acting onthe housing cup are not transmitted to the torsion spring and intertiahammer.

HERBERT H. ENGEMANN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,066,976 Holmes Jan. 5, 19372,468,332 Johnson Apr. 26, 1947

